The expression of retinoic acid receptors in lymph nodes of young children and the effect of all-trans-retinoic acid on the B cells from lymph nodes.

To elucidate the mechanism of vitamin A enhancing the production of antibody, we examined the expression and distribution of retinoic acid receptors mRNA in lymph nodes of young children ( < or = 5 years of age), and investigated the affection of all-trans-retinoic acid on the maturation and activation of the B cells isolated from the lymph nodes and cultured in vitro. Twenty-four normal lymph nodes were collected. By in situ hybridization, we found that all six retinoic acid receptor genes expressed and distributed widely in the lymph nodes, and the levels of mRNA for retinoic acid receptor genes (detected by RT-fluorescent quantitative PCR) were increased with the development of children. In vitro culture, all-trans retinoic acid promoted the maturation and activation of the B cells from the lymph nodes. Thus, promotion on B cells in lymph node may be the important mechanism of vitamin A reinforcing the humoral immunity in young children.